Quasi-Elastic Light Scattering from Muscle F-Actin

Abstract

Photon counting autocorrelation functions of light scattered from solutions of muscle F-actin were measured by use of a 128 channel digital correlator. Measured correlation functions showed highly non exponential decay, which came mainly from the existence of very slow decay components, much slower than 1 s -1 . These slow decay components were observed not to produce the occupation number fluctuation. The average decay rate, \(\bar{\varGamma}\), dispersion, \(\mu_{2}/\bar{\varGamma}^{2}\), and skewness, \(\mu_{3}/\bar{\varGamma}^{3}\), obtained by the cumulant expansion method were strongly dependent on the channel width of the correlator, and on the position in, and preparation of the solution. These results were discussed in relation to the existence of aggregates and exponential length distribution of actin filaments. It was shown that, in highly polydisperse samples, correlation functions should be measured at various channel widths, and that apparent non reproducibility of the results could be avoid...